Railway centralized traffic controlling apparatus



July 15, 1947. I A. L. JEROME RAILWAY CENTRALIZED TRAFFIC CONTROLLING APPARATUS Filed July 16, 1945 3 Sheets-Sheet l NYE. m5 mummw N Q W m v m .RQEQ .L \W @S 3% wg b w r ibk ML lflfluvllu Mk K .m .& w 3 W ml 4 July 15, '1947. A. 1.. JEROME RAILWAY CENTRALIZED TRAFFIC CONTROLLING APPARATUS Filed July 16', 1945 3 Sheets-Sheet 2 4 N MNNN b HIS ATTORNEY m E mw w m w Patented July 15, 1947 RAILWAY CENTRALIZED TRAFFIC CONTROLLING APPARATUS Arthur L. Jerome, Edgewood, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application July 16, 1945, Serial No. 605,284

11 Claims.

My invention relates to railway traffic controling apparatus and particularly to improved circuits for use in centralized trafiic control machines for remote control of traflic in track stretches in which traffic may move in either direction.

In application for Letters Patent of the United States, Serial No. 567,188, filed December 8, 1944, by Frank T. Pascoe and Arthur L. Jerome, which issued as Patent No. 2,411,387, November 19, 1946, there are shown interlocked circuits at the control office governed by the signal control levers which govern train movements into the opposite ends of a track stretch, so as to prevent interference with train movements in the event of improper manipulation of these levers and to prevent the reversal of the direction of traflic except when the single track stretch is unoccupied and the signals governing entrance of trafiic into the stretch are at stop.

An object of my invention is to provide an improved system of the type described, but which requires less apparatus than the system of the application identified above.

A further object of the invention is to provide a system of the type described which employs an auxiliary relay which'i operated in response to a change in the position of the master directional relay and which remain in its operated position until an indication code is received showing that traffic in the associated track stretch has been established in the direction designated by said master directional relay.

Another object of the invention is to provide a system of the type described in which the auxiliary relay, when operated, establishes circuits to energize the starting relays for transmitting control codes to the field stations at both ends of the associated stretch when the starting button for the station at either end of the stretch is pressed.

A further object of the invention is to provide a system of the type described in which the auxiliary relay, when operated, removes the master directional relay from the control of the block indication relays, and which when operated cancels the existing block indications.

Another object of the invention is to provide an improved system'of the type described in which the auxiliary relay controls the circuits of the block and directional indication lamps on the panel of the C. T. C. machine to prevent improper lighting of these lamps during a change in the direction of traffic in the associated stretch.

A further object of the invention is to provide an improved system of the type described which is arranged to insure that the auxiliary relay returns to its normal position if, following a change in the direction of trafiic in a track stretch, a train enters the stretch before an indication is transmitted to the office that the stretch has been prepared for the new direction of traffic.

Another object of the invention is to provide an improved system of the type described.

Other objects of the invention and features of novelty will be apparent from the following description taken in connection with the accompanying drawings.

I shall describe one form of railway signaling system embodying my invention and shall then point out the novel features thereof in claims.

In thedrawings,

Figs. 1A and 13 when placed together with Fig. 1A at the left, form a diagram of a stretch of single track railway equipped with wayside signaling apparatus governed by a centralized traffic control system, and

Fig. 2 is a diagram of a portion of the control machine at the ofllce.

In practicing my invention I provide in the .C. T. C. machine a normally released auxiliary relay for each track stretch and control it by the master directional relay andby the block and detector. section indication relays for the stretch. On movement of the contacts of the master directional relay a pick-up circuit is established for the auxiliary relay over a front contact of a block indication relay. When the contacts of the auxiliary relay move to their operated or picked-up position, the auxiliary relay releases or operates the block indication relay and establishes for itself one or the other of two stick circuits governed by the block indication relays and by the master directional relay depending on the position of the contacts of the master directional relay, while the efiective stick circuit is interrupted on receipt of an indication code which picks up the block indicationrelay which corresponds with the position of the master directional relay.

In addition, the circuit of the auxiliary relay is governed by the detector section indication relays to insure that the auxiliary relay releases or is restored to normal when a train enters the stretch. The auxiliary relay When operated or picked up establishes a circuit to permit operation of the master directional relay even though the block indication relays are released, while the auxiliary relay, when picked up, interrupts the circuits of the block and directional indicatlon lamps to prevent improper lighting of these group of relays.

the portions of the wayside apparatus essential,

to the understanding of this invention have been shown and the remainder of the equipment may be arranged as shown in application for Letters Patent of the United States Serial No. 501,254 of H. S. Young, filed September 4, 1943.

As shown, the wayside signals are of the wellknown Searchlight type and may be constructed as shown in Letters Patent of the United States No. 1,864,224 issued June 21, 1932, to W. B. Wells.

The equipment at the-left-hand or west end of the stretch includes a C. T. C. system field station unit designated station l-2, and the equipment at the right-hand or east end of the stretch includes a C. T. C. system field station unit designated station 3-4.

The field stations are connected with the ofiice over a pair of line wires, not shown, by a code communication system which may be of the type shown in Letters Patent of the United States No. 2,229,249, issued January 21, 1941, to L. V. Lewis, or in application for Letters Patent of the United States Serial No. 496,907, filed July 31, 1943, by A. P. Jackel, which issued as Pat. No. 2,411,375, November 19, 1946, and described in Manual 506A of The Union Switch and Signal Company, Swissvale, Pa.

Consideration of the detailed mode of operation of the code communication system is not needed" for an understanding of this invention and it is deemed sufilcient to point out that a field station is provided at each end of each track stretch to be controlled and that coding units are provided at the ofiice and at each field station and are connected by a pair of line wires,

not shown, over-which control codes are transmitted at times from the ofiice to a selected field station, and at other times indication codes are transmitted over the'same linewires from the different field stations to the office without interference. Transmission of each code includes the temporary establishment of a plurality of communication channels, such, for example, as seven between the oflice and a station to position a Each code includes a distinctive code call by means of which a selector relay l-2S or 3-48 at the oifice and a similar relay, not shown, at

one station only is energized to effect temporary establishment of seven communication channels between the ofiice and the station. The different stations have different code calls, consequently the selector relays for different stations or panels are not energized at the same time, and the same channels provide communication at different times with all of the stations. I

The explanation of this invention requires only three channels employed in the transmission of control codes and five channels employed in the transmission of indication codes, and in order to simplify the disclosure the other channels and related apparatus have not been shown. 7

In order to simplify Fig. 2 of the drawings, the terminal representing control or indication channels on the'office C. T. C. machine which is employed in connection with the field stations at both ends of the track stretch is in some instances shown as separate terminals for the two field stations, and in other instances is shown as a common terminal for both field stations. However, it should be understood that there is but one terminal on the C. T. C. machine for each control or indication channel, and that these terminals serve all of the field stations. The oflice machine operates to connect to these terminals the office equipment for the various field stations, but to connect only one station at one time.

' The channels employed in the transmission of control codes are designated 2, 5 and l, and the channelsemployed in the transmission of indication codes are designated Ii), l2, l3, l4 and I5, the numbers employed to designate these channels being the same as are employed to designate the corresponding channels in the aboveidentified application of H. S. Young.

It is to be understood that the system of this invention is made up of a number of unit portions generally similar to the one shown in the drawings, but as the invention may be fully understood from one such portion, only one has been illustrated in the drawings.

The office and field stations are each provided with a suitable source of direct current, not shown, the terminals of which are designated B and C in the drawings.

In most instances in the drawingsthe relay contacts are located directly in line with the Winding of the relay, but in some cases in order to simplify the drawings, relay contacts are separated from the relay winding and in these instances the relay with which the contacts are associated is designated by appropriate reference characters placed above the contacts.

The equipment at each field station includes a starting relay FST, which responds to a change in position of any of the associated indicating relays to provide connection from terminal B of a source of current to the indication channels to effect delivery of indication codes over the line .wires during the time that a delivery relay D at and these relays are controlled as explained in detail in the above-identified application of A. P. Jackel. The field station starting'relays are of the polarized type and each has contacts which normally occupy their left-hand or normal position from which they are moved to their righthand or reverse position to initiate transmission of an indication code. The starting relay 'contacts' are restored to their left-hand or normal position in consequence of the transmission of an indication code by the associated field station.

The indication relays at the oflice governed from the field station l--2, at the left-hand or west end ofithe single track stretch, include a relay ITK which controls a lamp' in the track diagram ofthe control machine to indicate the condition of occupancy of section IT, containing the track'switch. lW, the rela lTK being controlled by the track relay ITR for the track section; a signal indication relay ZRI-IK governed by the relay 2RRGP which repeatsthe stop indication of the signals 2RA and ZRB; and a block indicationrelayZRBK controlled by the relay ZRBP which is governedby trafiic. conditions in the stretch.

The relays at the field station 374 at the right-hand end of the single track stretch function. ina similar manner to control the relays 3'IK', ALI-1K and..4LBK at the office.

The block indication lamp BKE in the track diagram of the control machine is governed by the relays ZRBK and 4LBK, one of which at times indicates the condition ofv occupancy of the single track stretch, and the other of which at other times indicates the condition of occupancy of the single track stretch.

. The signal levers 2SIG and 481G on the panel of the control machine are the usual three-position levers for the code control of the signal control relays at the field stations at the opposite ends of the stretch. The signal levers 'ZSIG and ISIG are electrically interlocked with respect to the control of train movements into the intervening single track stretch by electroresponsive means in the form of the master directional polarized relay 2-4LP, as in, the above identified application of H, S. Young and also in his Letters, Patentof the United States No. 2,326,991.

The relay 24LP has associated therewith the normally released auxiliary relay 2 lLPSR which is provided by this invention and is controlled in the manner explained below.

The push buttons E2STB and 3-4STB are the starting buttons for operating the usual code starting relays l-ZST and 3-4 ST by means of which control codes are initiated and the corresponding stations selected. Each starting relay, when actuated or energized, initiates av control code as described in Lewis Patent No. 2,229,249 including a code call for energizing the selector relay .8 for the same panel. Each selector relay, when energized, releases or restores to normal the associated starting relay and connects terminal B of a local source of energy to selected ones of the control .channels in accordance with the positions of the signal levers and of contacts of the master directional relay 24LP.

The equipment is arranged so that when energy is applied to channel 2 and a control code is transmitted to afield station the contacts of the trafiic directional relay FS at that station are operated to their normal position to condition the wayside apparatus to make that end of the stretch an exit or leaving end. Similarly, the equipment is arranged so that, when energy is not applied to channel 2 and a control code is transmitted to afield station, the contacts of the traffic direction control relay F8 are operated to their reverse position to condition the wayside apparatus to make that end of the stretch an entrance end so that the signal at that point may be controlled by the wayside circuits on operation of the associated signal relay.

The equipment is also arranged so that, when energy is supplied to the code channel governing a signal control relay, such as, for example, channel 5 or 1, and a control code is transmitted to a field station, the signal control relay at that station is operated to render the signal subject to the control of the wayside circuits. When energy is not supplied to the code channel governing a signal control relay, and a control code is transmitted to a field station, the signal control relay at that station is operated to keep the signal at stop irrespective of the wayside circuits.

,The signal levers Z-SIG' and ASIG are of the three-position type and each has. a normal center position N, a left-handposition L, and a righthand position R1. These levers control contacts which are; shown diagrammatically in the drawings, thev contacts which are closed in the lefthand position of the lever being designed L; those which. are closed in the right-hand position of the lever being designated R; those which are closed in either the normal or the left-hand position of the lever being designated NL; and those which are closed in either the normal or the right-hand position or the lever being designated NR.

The equipment isshcwn in the condition which it assumes when the track stretch is vacant, the signals 22R and 4L are at stop, and the signaling apparatus prepares the stretch for westbound trafiic. At this time the contacts 20 and 2| of the traflic directional relay ZWFSR at the lefthand or west end of the stretch are in their lefthand .or normal positions and connect the line wires 23 and 24 over contacts 25 and 26 of relay ZLPC to asource of energy. The relay ZLPC', not shown, is governed in the well-known manner in accordance with the aspect displayed by signal 2L and controls the polarity of the energy supplied to the line wires 23 and 2 5. The energy suppliedto the line wires 23 and 24 feeds over front contacts of track relays ITR, 2TB, and 4TB, over back contacts 2! and 28 of relay SRPC, and back contacts 30 and 3! of relay BRSR to the winding of signal EL and causes this signal, when lighted, to display its yellow or caution indication.

At this time signals ZRA and ZRB are at stop so the circuit of relay ZRRGP is complete and its contact 35 interrupts the supply of energy to terminal l5 of the C. T. C. system field station unit, and, as section IT is vacant, contact 36 of relay lTR is picked up and interrupts the supply of energy to terminal 19 of the field station unit. As the contacts of relay ZWFSR. are in their normal position, the circuit of relay ZRI-ID is interrupted and its neutral contact 33 interrupts the supply of energy to relay 2RBP and its contact Ifil is released and. interrupts the supply of energy to terminal Id of the field station unit. Accordingly, the indication codes sent to the office from station l2 release relays ITK, ZRHK and. ZRBK.

As signal 6L is conditioned to display its caution indication energy is supplied over its front contact Y to relay ELPC and its contacts are picked up to cause energy of normal polarity to be supplied to line Wires All and 4! leading to relay ALI-ID. At this time wire M is connected to terminal C over front contact Q2 of relay ELPC, and wire 4!] is connected over front contact 43 of relay BLPC, winding of relay fiLAR', and back contacts G and Y of signal 6R to terminal B. The energy supplied to line wires 46 and 4! through the winding of relay SLAB keeps its contact 45 picked up to interrupt the supply of energy to the lamp of signal 6L.

The energy supplied to line wires 40 and 4! is supplied over front contacts of track relays 5TB, 6TB. and 3TB, and reverse polar contacts 50 and 51 of relay EFSR to the winding of relay iLHD and picks up the relay neutral contacts and moves the relay polar contacts to their left-hand or normal positions so that energy is supplied over normal polar contact 53 and neutral contact 54 to relay, lLBP and its contact 55 establishes the circuit for supplying energy to terminal [2 of the field station unit.

As shown, the. contacts 58 and as of relay dLHSR are in their normal positions and interrupt the circuits for supplying energy to the windin sg .Of signals 4LA and ALB and these signals are both at stop and establish the circuit of relay 7 GLRGP so that its contact 56 interrupts the supply of energy to terminal l3 of the field station unit. As section 3T is vacant, track relay 3TB,

is picked up and its contact 51 interrupts the cirrelay lLBK is picked up, energy may be supplied to one or the other of the windings of the relay 2--4LP on movement of the signal lever 2SIG or 481G to thereby move the contacts of relay 2--4LP if the operator wishes to change the designated traffic direction.

If it is desired to clear one of the signal 4L, the lever GSIG is moved to its left-hand position and the starting button 34STB is pressed to establish a pick-up circuit for the starting relay 3-4ST and it picks up or is actuated to establish a stick circuit for itself and to initiate operation of the office coding unit to transmit a control code to the field station at the right-hand end of the stretch. At the time the starting button 34STB is depressed its contact 63 is closed, but as relay 24LPSR is released, its contact 64 interrupts the circuit for supplying energy to relay I-ZST and it is not actuated'but remains released and does not cause a control code to be sent to the field station at the left-hand end of the stretch. This is desirable as there is no reason to send a control code to this station at this time since the stretch is' assumed to be prepared for westbound traffic.

The control code transmitted as a result of picking up of relay 34ST causes a selector relay 34S to pick up with the result that the code sent to station 3-4 is determined by the condition of control circuits individual to this station. This is the case since energization of the input terminals of the office coding unit is governed by circuits including front contacts of the selector relay 34S, and when relay 3-4S is picked up, the selector relay I-2S, and all other selector relays, not shown, are released. When relay 34S picks up terminal B of the battery is connected over normal polar contact 56 of relay 2-4LP, front contact 61 of relay 3-48 and a contact L of lever 4SIG to channel 5 and a control code i transmitted to field station 3-4 to reverse the contacts of relay 4Ll-ISR. v

When relay 3--4S.picks up, its front contact 69 is closed but energy is not supplied to channel 2 as contact 86 of relay 2-4LP is in its normal position. Accordingly, the control code sent to sta-. tion 3-4 maintains the contacts of relay dEFSR in their reverse position.

On reversal of the contacts 58 and 59 of relay lLl-ISR energy is supplied to the winding of signal 4LA over the circuit controlled by neutral and polar contacts of relay 4LHD and by contacts 90 and SI which are governed in accordance with the position of switch 3W so as to establish the circuit of signal 4LA when and only when the switch is in its normal position. As shown, the switch 3W is in its normal position and the polar contacts of relay 4LHD are in their normal posi- 'tion so that energy is supplied to the winding'of signal 4LA to cause it'to display its green or clear indication. When signal 4LA clears the circuit of relay 4LRGP is interrupted and it releases to cause energy to be supplied over its back contact 56 to terminal I3 of the field station unit while a contact of relay lLRGP momentarily interrupts the circuit of the starting relay 3--4FST to cause an indication code to be sent to the oflice to pick up relay 4LHK to show that signal 4LA has cleared.

When relay 4LHK picks up, it establishes a stick circuit for itself, while its contact Ill interrupts the circuits of relay 2-4LP and thereby prevents movement of the contacts of relay 2- 4LP and insures that it maintains traffic in the established direction.

If a train accepts the signal and enters the stretch, the track relay 3TH will release to interrupt the circuit of relay 4LI-ID and contact 51 of relay 3TB establishes the circuit for supplying energy to terminal ID of the field station, while a contact of relay 3TB interrupts the circuit of slow release relay 3TP. After release of relay 3TB. and prior to release of relay 3TP, energy is supplied over back contact 12 of relay 3TB. and front contact 13 of relay 3TP to the lower winding of relay 4LHSR and moves the relay contacts 58 and 59 to their normal positions in which they interrupt the circuit of signal 4LA to prevent reclearing of signal 4LA unless the contacts of relay GLHSR are reversed by a control code transmitted from the ofiice.

On release of relay 4LHD its contact 53 interrupts the supply of energy to relay 4LBP and it releases to interrupt the supply of energy to terminal l2 of the field station unit, while, when signal 4LA displays its stop indication, the circuit of relay lLRGP is complete and its contact 56 is picked up to interrupt the supply of energy to terminal 13 of the field station unit. On movement of the contacts of relays 3TB, 4LRGP and 4LBP the circuit of the starting relay 3-4FST is momentarily interrupted and its contacts are reversed to cause an indication code to be sent to the office to pick up relay 3'I'K and to release relays 4LHK land dLBK. When relay 3TK picks up, its

contact 15 establishes a circuit for lighting the lamp 3TKE, while, when the contacts of relay 4LBK move to their released or second position, its contact 16 establishes the circuit for lamp 2-4BKE and it is lighted to show that the block is occupied. Inaddition, when relay 3TK picks up; its contact 18 interrupts the circuits of relay 2'4LP, while the circuits of relay 2-4LP are also interrupted on release of contact 19 of relay ALBK.

the track relays 6TH and 5TR release to interrupt the line wires 40 and 4| and thus maintain relay 4LHD deenergized.

When the train vacates section 3T, the track relay 3TH picks up and its contact 51 interrupts the supply of energy to terminal ID of the field station unit so that the indication code sent to the office releases relay 3TK to extinguish lamp 3TKE While contact 18 in the circuits of relay r -4H is closed. At this time the contacts of relay 4LBK remain in their second or released position and its contact 19 interrupts the circuits of relay 24LP to prevent movement of its contacts. The relay ALBK is effective to lock the relay 24LP at this time as the contacts of relays ZRBK and 2'4LPSR are released.

When the train enters section 4T, the track relay ETR. releases and energy is supplied to the relay BLSR over the circuit which includes track contact 89 of relay 4TH, and front contact 85 of relay GLPC. Accordingly, relay BLSR picks up and establishes a stick circuit for itself which is effective as long as either relay 4TR or relay SLPC is released.

On release of relay '4TR the supply of energy over line wires 23 and 24 to the winding of signal 6L is cut oil" and the signal displays its stop indication and interrupts the circuit of relay B-LPC and it releases so that energy of reverse polarity is supplied to the line wires 49 and 4| over back contacts 43 and 42 of relay 6LPC, front contacts of relay GLSR, winding of relay BLA R, and back contacts G and Y of signal BR. When the train vacates sections ET and T the track relays 'GTR and 5TB pick up and complete the circuit of the line wires 49 and 4| and energy is supplied to relay '4LHD to pick up its neutral contacts and move its polar contacts to their right-hand or reverse position so that, if the contacts of relay ALHSR are reversed to clear signal lLA, this signal will display its yellow or caution indication. As the contact 53 of relay 4LHD is in its reverse position it does not establish the circuit of relay 4LBP and it remains released and its contact 55 interrupts the circuit leading to terminal l2 of the field station unit and indication codes sent to the ofiice do not pick up relay AL-BK.

Movement of the westbound train out of the stretch is governed by signal 2L which may be controlled from the oifice by the operator in any suitable manner. The details of the control of this signal are not essential to an understanding of this invention and are being omitted to simplify this disclosure.

If signal 2L is now cleared to permit the train to pass out of the single track stretch, the train may advance into section IT so relay lTR releases and its contact 36 establishes the circuit leading to terminal I9 of the field station unit and an indication code is sent to the office to pick up relay ITK. When relay ITK picks up, its contact 85 interrupts the circuits of relay 2'4LP and contact 81 of relay I'IK establishes the circuit of the lamp ITKE.

When the train vacates the stretch so that relays ITR, 2TB and 4TB pick up, energy is supplied over line wires 23 and 24 to the winding of signal 5L to cause it to display a permissive indication so that the circuit of relay BLPC is established and it picks up to release relay GL'SR and to cause energy of normal polarity to be supplied to the line wires '49 and '45. This energy keeps the neutral contacts of relay lLHD picked up and moves the polar contacts of the relay to their lefthand or normal position with the result that contacts 53 and 54 establish the circuit of relay lLBP, and it picks up to establish the circuit for supplying energy to terminal IQ of the field station unit. Accordingly, an indication code is sent to the ofiice which moves the contacts of relay 4LBK to their first onpic-ked-up position to close its contacts 19 in the eirepits of the relay 2-4LP and to cause ifil fiffiis'lrfisflf riser tte sitminternuphthe circuit 10 not been cleared and section 3T is unoccupied, the indication code sent to the oflice at this time keeps relays lLHK and 3'IK released so their contacts in the circuits of relay Z- lLP are closed.

When the train vacates section IT and track relay lTR picks up, an indication code is sent to the ofiicefr'om field station l2 to release relay lTK, thereby extinguishing lamp ITKE and closing back contact 86 in the circuits of relay 2-'4L[P. Accordingly, the circuits of relay 24LP are now complete and energy may be supplied to one or the other of the relay windings on movement of one of the signal levers.

If the operator wishes to change traffic in the stretch from westbound to eastbound, he may do so by placing lever 4SIG in either its center position N or its right-hand position R, and mov ing the lever ZSIG to its position R. so that energy is supplied to the upper Winding of relay 2--4LP. This energy moves the relay contacts to their right-hand or reverse position with the result that energy is supplied over reverse polar contact 88 of relay 2- 4LP, front contact 89 of relay 4133K, and back contacts 99 and 9| of relays ITK and 3TK to relay 24LPSR and its contacts move 'to their operated or picked-up position. When relay 24LPSR picks up, its contact 92 interrupts the stick circuit for relay 4LBK and after a short time the contacts of relay 4LBK move to their released or second position to interrupt the circuit traced above for energizing relay 2RLPSR. However, when relay 2-4LPSR picked up, its contact 93 established a stick circuit including reverse polar contact 88 of relay 2-4LP, back contact 94 of relay ZRBK, and back contacts 99 and '91 of relays ITK and '3TK, so the relay 2-6LPSR remains energized or operated after release of relay -4LBK.

When relay 24IESR picks up, its contact 95 establishes a connection shunting contact 19 of relay 4LBK in the circuits of relay 2-4111, so the operator, having secured control of relay 24LP, retains his control of this relay after release of relay ALBK, and can restore the contacts of relay 2--'4LP to their left-hand or normal position if he decides to restore westbound traific in the track stretch. If, while relay 24LPSR is picked up, the contacts of relay 2-4111 are moved to their left-hand position, the relay 2 4LPSR will be maintained operated or energized by current supplied over the stick 'c'ircuit which includes normal Ipolar contact 98 of relay 2-4LP, front contact 91 of relay 24IPSR, back contact 89 of relay '4LBK, and back contacts 99 and 9| of re-lays ITK and 3TK. Accordingly, contact 96 of relay 2-4LPSR maintains the connection shunting the contacts of relays '4LBK and 'ZRBK in the circuits of relay 2'4LP. During movement of the contact 89 of relay 24LP between its two positions the supply of energy to relay 2-ELPSR is interrupted, but this interruption is very brief and relay 2-4LPSR has a resistance connected across its terminals to render it slow to release so the relay contacts remain picked up and maintain the relay stick circuits during this momentary interruption of the supply of energy to the relay winding.

When relay 2-4LPSR picks up, its contact '98 interrupts the circuits of the lamps WFE, EFE and 2-4BKE, while its contacts 64 and 99 establish the circuits for the starting relays l-2ST and 34ST so that both starting relays are energized or actuated if either starting cbutton ilhszsmoscfireefifimBidsipressecloc cl guana tun.

that the contacts of relay 2-4LP are permitted to remain in their right-hand position in which they designate east-bound traffic in the stretch, that lever ZSIG is in its position R, and that starting button |--2STB is pressed, thereby energizing relays I--2ST and 34ST to cause control codes to be sent to the field stations at both ends of the stretch sequentially.

During transmission of the control code to station |-2 energy is not supplied to channel 2 since normal polar contact 66 of relay 2-4L P is open, but energy is supplied to control channel I over reverse polar contact 66 of relay 24LP, front contact I of relay |2S, and a contact R of lever ZSIG. Accordingly, the contacts of relay ZWFSR are moved to their reverse positions, while the contacts of relay 2Rl-ISR are also moved to their reverse positions.

When the control code is sent to station 34 energy is supplied to channel 2 over reverse polar contact 66 of relay 24LP and front contact 69 of relay 34S, while energy cannot be supplied to channel since normal polar contact 66 of relay 2-4LP is open. Accordingly, the contacts of relay 4EFSR are moved to their left-hand or normal position, 'while the contacts of relay ALI-ISR are maintained in their normal position.

On movement of the contacts of relay EWFSR to their reverse position the supply of energy to line wires 23 and 24 is cut off and these wires are connected to relay ZRHD. When the supply of energy to wires 23 and 24 is out 01f, the signal 6L goes to stop and interrupts the supply of energy to relay 6LPC and it releases to cut on the supply of energy to line wires 40 and Al, and to interrupt the pick-up circuit of relay BLSR to insure that it remains released.

When the supply of energy to line wires 40 and 4| is cut ofi, the relay ALHD releases, if it is not already released, because of interruption of its circuit due to movement of contacts 50 and 5| of relay 4EFSR to their normal positions. When relay 4LHD releases, its contact 54 interrupts the circuit of relay ALBP and it releases so that its contact 55 interrupts the circuit leading to terminal I2 of the field station unit and indication codes thereafter sent from this station to the office do not pick up relay ALBK.

When the contacts 50 and 5| of relay iEFSR are moved to their normal position energy of one polarity or the other is supplied to line wires 40 and 4|. The polarity of the energy supplied to wires 40 and 4| is governed by contacts of relay 4RPC, not shown, which is controlled in the usual manner in accordance with the indication displayed by signal 4R.

The energy supplied to line wires 40 and 4| feeds over back contacts of relays 6LPC and BLSR to the winding of signal BR and conditions this signal, when lighted, to display an appropriate permissive indication, while the contacts of the signal establish a circuit for relay SRPC and it picks up to establish the circuit for supplying energy of normal polarity to line wires 23 and 24 in series with the winding of relay GRAB. Accordingly, relay BRAR is picked up and its contact interrupts the circuit of the lamp of signal 6R.

The energy supplied to line wires 23 and 24 is supplied over reverse polar contacts 20 and 2| of relay ZWFSR to relay 2RI-ID and picks up its neutral contacts and moves its polar contacts to their left-hand or normal position with the result that energy is supplied over its contacts 34 and 35 to relay ZRBP and it picks up so that its con- 12 tact lei establishes the circuit leading to terminal M of the field station unit. As the contacts of relay ZRI-ISR are assumed to be reversed, energy is supplied to signal ZRA or 2313, depending on the position of switch lW, after energiza-- tion of relay ZRHD, and when one of these sis nals clears the circuit of relay 2RRGP is interrupted and it releases so that its contact 35 establishes the circuit leading to terminal I5 of the field station unit.

As a result of the changes at station |-2 the starting relay |-2FST is reversed and an indication code is sent to the ofliceto pick up relays- ZRBK and 2RHK.

At the time the indication code from station |-2 is received at the oifice, the delivery relay |-2D picks up and a contact of relay |-2D connects a terminal of the winding of relay ZRBK to channel i4 so that relay 2RBK is picked up by energy supplied thereto over channel 14. When the contacts of relay ZRBK move to their first or picked-up position, contact 94 interrupts the stick circuit over which energy is supplied to auxiliary relay 2-4LPSR when contact 88 of relay 24LP is in its reverse position so the contacts of relay 24LPSR move to their normal or released position after a short time interval and additionally interrupts its own stick circuits, while back contact 62 of relay 24LPSR is closed to provide the stick circuit for relay 2RBK after release of relay |2D. The operating characteristics of the C. T. C. system oifice equipment are such that the relay |--2D is picked up for a period substantially longer than the release time of relay 24LPSR even though release of relay 24LPSR is delayed by the resistor connected across the terminals of the relay winding. Accordingly, when the indication code is received from station |-2, the relay 24LPSR is certain to release and prepare the stick circuit for relay ZRBK before the relay |2D releases to interrupt the pick-up circuit for relay 2RBK.

When the contacts of relay ZRBK move to their first or pick-up position, its contact I04 interrupts the circuit of lamp 2-4BKE to prevent lighting of this lamp after release of contact 98 of relay 2--4LPSR. When the contacts of relay 24LPSR move to their normal or released position energy is supplied over its back contact 98 and reverse polar contact I02 to lamp EFE and it is lighted to shoW that the stretch has been prepared for eastbound traffic. In addition, when relay 2--4LPSR releases, its contacts 64 and 99 interrupt the circuits for the starting relays |2ST and 3-4ST so that each of these relays is now controlled only by its own starting button.

When relay 24LPSR releases, its contact 96 in' the circuits of relay 24LP is open, but at this time contact I03 of relay ZRBK is closed and provides a connection shunting contact 96 of relay 24LPSR, so energy may be supplied to relay 24LP if the circuits of this relay are not interrupted by one of the other indication relays. Since it was assumed that one of the signals 2R was cleared and that the indication code sent to the ofiice picked up relay ZRHK, contact I05 of relay ZRHK interrupts the circuits of relay 24LP and thus insures that the contacts of relay 24LP will remain in their right-hand position and maintain eastbound traffic in the stretch.

Because of code congestion on the C. T, C. line circuit the indication code from station |-2 may not be sent to the office for a substantial time interval after the stretch has been prepared for eastbound traffic and one of the signals 23 gov- 13 erning entrance of traffic into the stretch has been cleared. Under these conditions, a train may accept the signal and enter the stretch before an indication code is sent to the office to show that the stretch ha been prepared for eastbound trailic. After the train enters the stretch, the relays ZRI-ID and ZRBP are released so that indication codes thereafter sent to the ofiice do not pick up relay ZRBK. However, when a train enters the stretch, relay l TR releases and its contact 3B establishes the circuit leading to terminal ID of the field station unit so that indication codes sent to the office pick up the relay ITK. The relay ITR may have associated therewith means, not shown, but well known in the art, for maintaining the supply of energy to terminal H] of the field station after release of relay ITR until at least one indication code is sent to the office. When relay ITK at the oifice picks up, its contact 9i] interrupts the circuit of the relay 2-4LPSR and its contacts move to their released or normal position to establish the circuits of the lamps 2-4BKE and EFE, and to open contact 9t of relay 24LPSR and thus render contact I03 of relay ZRBK effective to control the circuits of relay 2-4LP so that relay 2-4LP will maintain eastbound trafilc in the stretch as long as relay 2RBK is released to indicate that the stretch is occupied.

On movement of an eastbound train through the stretch the equipment operates in substantially the same manner as during movement of a westbound train through the stretch and a detailed explanation of the operation of the equipment at such times is unnecessary.

If, while the stretch is prepared for eastbound traific and relay ZRBK at the oflice is picked up, the contacts of the relay 2-4LP are moved to their left-hand position to designate westbound trafiic, the relay 24LPSR will be picked up or operated by energy supplied over the normal polar contact 88 of relay 2-4LP and front contact 94 of relay ZRBK. As soon as relay 2-4LPSR picks up, its contact 9'! establishes the stick circuit includingback contact 89 of relay lLBK, while contact 62 of relay 24LPSR interrupts the stick circuit for relay ZRBK so that it releases and prepares for relay 24LPSR, the stick circuit which is efiective when contact 88 of relay 2--4LP is in its reverse position. The equipment thereafter operates in substantially the same manner as during establishment of eastbound trafiic and a detailed explanation of its operation is unnecessary.

As explained above, when the stretch is prepared for westbound trafiic, 'is unoccupied, and the signals 4L are at stop, the contacts of relay 2-4LP may be moved to their right-hand position to designate eastbound trainc in the stretch. On this movement of the contacts of relay 2-4LP the relay 24LPSR is operated or picked up, thereby releasing relay 4LBK and establishing for itself a stick circuit governed by relay ZRBK.

After movement of the contacts of relay 2-4LP to their right-hand position, in which they designate eastbound traffic in the stretch, the wayside equipment continues to condition the stretch for westbound traflic until control codes are transmitted to the field stations at the ends of the stretch. If, after movement of the contacts of relay 24LP to their right-hand position, the

operator does not press one of the starting buttons for a time interval, an indication code may be sent from station 3-4 to the office. This indieation eodetwilr causexrelay mmlo tc'rll'piokadp tlilrfiitl-ililiko'fiufi nine eoaenven aeaaicmm 14 However, picking up of relay 4LBK does not release relay 2-4LPSR since relay 2-4LPSR. is energized by current supplied over the stick circuit which includes reverse polar contact 88 of relay 24LP, its own front contact 93 and back contact 94 of relay ZRBK. Accordingly, relay 2-4LPSR remains picked up and interrupts the stick circuit for relay 4LBK so that on release of the delivery relay 34D the relay 4LBK also releases, while th relay 2--4LPSR maintains the circuits for the starting relays and for relay 2-4LP, and interrupts the circuits of the lamps 24BKE, EFE and WFE.

If a starting button is now pressed, control codes will be sent to the stations at both ends of the stretch and the wayside equipment will prepare the stretch for eastbound traffic and the equipment will thereafter function as explained above.

The equipment operates in a similar manner if, while the wayside equipment prepares the stretch for eastbound traffic, the contacts of relay 24LP are moved to their left-hand. position in which they designate westbound trafiic in the stretch, but pressing of a starting button is delayed so an indication code is sent from station !-2 to the office and picks up relay ZRBK. When the contacts of relay 24LP are in their lefthand position, the relay 2-4LPSR is energized by current supplied over the stick circuit which includes normal polar contact 88 of relay 24LP, its own front contact 91, and back contact 89 of relay 4LBK. As relay 2--4LPSR is energized by current supplied over a circuit independent of relay ZRBK, the reIay 2-LPSR is not affected by picking up of relay ZRBK, and remains picked up and interrupts the stick circuit for relay 2RBK.

It may happen that after control codes are sent to change the direction of traffic in the stretch, but before an indication code has been sent to the office to show that the new direction of traffic has been established, the operator may decide to restore the original direction of traflic and for this purpose he will return the contacts of relay 2-4LP to their original position, and he may not press a starting button for some time thereafter. For purposes of illustration, assume that the stretch is prepared for westbound traffic, that relay 24LP is operated to designate eastbound traliic in the stretch and that control codes are transmitted for this purpose. The operator may now move the contacts of relay 24LP to their normal or left-hand position to again designate westbound traffic, but may not press the starting button immediately. After the wayside equipment responds to the control codes and prepares the stretch for eastbound traflic, an indication code may be sent to the ofllce to pick up relay ZRBK, but this will not release relay 2-4LPSR since after movement of the contacts of relay 2--4LP to their normal position the relay 2-4LPSR is energized by current supplied over the stick circuit controlled by relay 4LBK and is not affected by relay 2RBK.

The equipment operates in a similar manner if, after transmission of control codes to prepare the stretch for westbound trafiic, the contacts of relay 2-- 4LP are returned to their right-hand position to designate eastbound traffic and control codes are not transmitted for a short interval.

From the foregoing it will be seen that the auxiliary relay 2 --4LPSR is picked up or operated on mowementrof the contacts of relay 2-4LP, and reamipinked aacmcoerat diremain esi tedroe ammaaeindicenen compensated-atmosphere that trafiic has been established in the direction designated by the relay 2- lLP. This insures that, until traffic is established in the designated direction, the relay 2-4LPSR will maintain the circuits for the starting relays and cause control codes to be sent to both ends of the stretch when the starting button for the station a either end of the stretch is pressed. This insures that the equipment will operate promptly and positively to prepare the stretch for trafiic in the direction des ignated by relay 2 4LP, while it also insures that relay 24LPSR will maintain the circuits for relay 2-4LP until preparation of the stretch for trafiic has been completed.

In addition, it will be seen that if following a change in the designated traffic direction a train enters the stretch before an indication code can be sent to the ofli'ce, theoccupied detector section indication code which is thereafter sent tothe ofiice will release the auxiliary relay 2-4LPSRl and thereby cause the block indication relays to control the relay 2-4LP so that the designated trafiic direction cannot be changed during occupancy of the stretch.

Although the invention has been illustrated and described in connection with a stretch of track equipped with wayside signaling apparatus governed over line wires, the invention is also applicable to stretches equipped with other forms of wayside signaling apparatus, such, for example, as coded track circuit signaling equipment.

Although I have illustrated and described one form of railway signaling apparatus embodying my invention, it should be understood that various changes and modifications may be made therein within the scope of the appended claims Without departing from the spirit and scope of my invention.

Having thus described-my invention, what I claim is:

1. In a system of centralized traffic control for a stretch of single track railroad between the ends of adjacent passing sidings, electroresponsive means at a remote control office for designating the direction of trafiic in said stretch, an auxiliary relay at said ofiice having contacts which have a normal and an operated position, a code communication system including a field station at each end of said stretch connected with said office, a system of reversible circuits extending the length of said stretch for controlling signals governing entrance of traffic into said stretch in accordance with trafiic conditions in the stretch, means at the ends of said stretch governed through said code communication system in accordance with the condition of said electroresponsive means for conditioning said system of reversible circuits to prepare the stretch for one direction of traffic or the other and to also control the transmission of block indication codes from one field station only for one direction of traffic and from the other field station only for the other direction of traffic which show when the entire stretch is unoccupied, a block indication relay at the office for each end of said stretch governed by the block indication codes transmitted from the field station at the corresponding end of the stretch, the contacts of each block indication relay being moved to their first or their second position during receipt of an indication code according as the indication code does or does not show that the stretch is unoccupied, means for each of said block indication relays effective during the intervals between receipt of indication codes for controlling said relay and operative after movement of the relay contacts to their first position to cause the relay contacts to remain in their first position as long as the contacts of said auxiliary relay remain in their normal position and to cause the block indication relay contacts to move to their second position on movement of the auxiliary relay contacts to their operated position, circuit means for moving the contacts of said auxiliary relay to their operated position when said electroresponsive means is operated to change the designated direction of traffic, means for moving the contacts of said auxiliary relay to their normal position when the block indication relay which shows traffic conditions in the stretch for the traffic direction designated by said electroresponsive means responds to an unoccupied indication code, and means for operating said electroresponsive means to change the designated direction of traffic only when the contacts of one of said block indication relays are in their first position or the contacts of said auxiliary relay are in their operated position.

2. In a system of centralized trafiic control for a stretch of single track railroad between the ends of adjacent passing sidings, manually controlled electroresponsive means at a remote control oifice for designating the direction of traflic in said stretch, an auxiliary relay at said oflice having contacts which have a normal and an operated position, a code communication system including a field station at each end of said stretch connected with said ofiice, a system of reversible circuits extending the length of said stretch for controlling signals governing train movement into and through said stretch in one direction or the other in accordance with traffic conditions in said stretch, means at the ends of said stretch governed through said code communication system in accordance with the condition of said electroresponsive means for conditioning said system of reversible circuits to prepare the stretch for one direction of trafiic or the other and to also control the transmission of block indication codes from one field station only for one direction of traffic and from the other field station only for the other direction of trafiic which show when the entire stretch is unoccupied, a block indication relay at the office for each end of said stretch governed by the block indication codes transmitted from the field station at the corresponding end of the stretch, the contacts of each block indication relay being moved to their first or their second position during receipt of an indication code according as the indication code does or does not show that the stretch is unoccupied, means for each of said block indication relays effective during the intervals between receipt of indication codes for controlling said relay and operative after movement of the relay contacts to their first position to cause the relay contacts to remain in their first position as long as the contacts of said auxiliary relay remain in their normal position and to cause the block indication relay contacts to move to their second position on movement of the auxiliary relay contacts to their operated position, circuit means for moving the contacts of said auxiliary relay to their operated position when said electroresponsive means is operated to change the designated direction of trafiic, means for moving the contacts of said auxiliary relay to their normal position when the block indication relay which shows traffic conditions in the stretch for the trafiic direction designated by said electroresponsive means responds to an unoccupied in- 17 'dication code, a starting relay at the office for each endof the stretch. adapted when actuated t'o-initiate transmission of a controlcode to the field station at the associated end of the stretch, and a starting. button for each starting relay, each starting. button controlling a circuit for actuating the associated starting. relay and also controlling. a circuit for. actuating the. starting relay for'the other. end of the stretch provided the contacts of said auxiliary relay are in their operated position.

3. In a system of centralized trafiic control for a. stretch of single track railroad. between the ends of: adjacent passingsidings, manuallycontrolled electro-responsivemeans at a remote control ofiicefordesignating the direction of trailic in 'saids-tretch,. an auxiliary relay at. said ofties having contacts which have a normal and an operated position-,la. code communication systemiincluding a field station at each end of said stretch connected with said office, a system of reversible circuits extending. the length of said stretch for controlling signals governing train movement into: and through said stretch in one direction or. the other in accordance with traffic conditions in said: stretch, means at the endsof said stretch governed through said. code communlcation' system inaccordancewiththe condition of said electroresponsive means for conditioning said system of reversible circuits to prepare the stretch for: one direction of trafiic or the other and to-also control the transmission of block indication codes from one field station only for one direction of traffic and from the other field station only fo the other direction of tralfic which show when the entire stretch is unoccupied, a block indication relay atthe ofiice for each end of'said stretch governed by the block indication codes transmitted from the field station at the'con'esponding end of: the stretch,.the contacts of each block indication relay being moved tothGirfirst. or their'second position during receipt of an indication code according as the indictation code does or does not show that the stretch is unoccupied, means for each of said block indication relays effective during the intervals between receipt of indication codes for controlling said relay and operative after movement of the relay contacts to their first position to cause therelay contacts tov remain in their first position as long as the contacts of said auxiliary relay remain in. their normal position and to cause the block indication relay contacts to move to: their second position on movement of the auxiliary relay contacts to their operated position, circuit means for" moving the contacts of said auxiliary relay to thei operated position when said electroresponsive means is operated to change the designated direction of trafiic, means for moving the contacts of said auxiliary relay to their normal position when the block indication relay which shows trafiic' conditions in the stretch for the traific direction designated by said electroresponsive means responds to an unoccupied indication code, and means governed by said electroresponsive means for indicating the designated direction of trafllc in said stretch provided the contacts of said auxiliary relay occupy their normal position.

4. In a systemof centralized trafiic control for a stretch of single track. railroad between the ends of adjacent passing sidings, electroresponsive means at a remote control. ofilce for designating the direction. of trafiic in said stretch, an auxiliary relay at said ofllce having contacts which have .a, normal and an operated position, acode communication system including a field station at each end of said stretch connected with said office, a system of reversible circuits extending thelength of said stretch for controlling signals governing train movement into and through said. stretch in one direction or the other in accordance with traffic conditions. in said stretch, means atthe ends of said'stretch governed through said code communication system inaccordance with the condition of said electroresponsive means for conditioningsaid system of reversible circuits to prepare the stretch for one direction. of trlaific or the other and to also control the transmission of block indication codesfrom one field station onlyfor one direction of traffic and from the other field station only for the other direction of traffic which show when the entire stretch is unoccupied, a, block indication relay at the ofiice for each end ofsaid stretch governed byth e'block indication codes transmitted from the field station at the correspondingend ofthe stretch, the contacts of each block indication relay" being moved to their first or their second position during receipt of an indication code accordingas the indication code does or does not show that the'stretch is unoccupied, means foreach of said 'block indication relays effective during the intervals between receiptof indication codes for controlling said relay and operative after movement of the relay contacts to their first position to cause the relay contacts to remain in their first position as long as the contacts of said auxiliary relay remain in thei normal position and to cause the block indication relay contacts to move to their secondposition on movement oi the auxiliary relay contacts to their operated position, circuit means for moving the contactsofsaid auxiliary relay to their operated position when said electroresponsive means is operated tocl'langethe designated direction of trafii'c, means fo moving the contacts'o'f said auxiliary relay to their normal position when the block indication relay which. shows traffic conditions in'the stretch for the trafii'c direction designated icy said electroresponsive means responds-to an unoccupiedjindication code, andmeans for operating said electroresponsive means tochange the designated direction of traflic only when the contacts of one of said block indication relays are in their first position or the contacts of said auxiliary relay are in their operated position.

' 5.1 In a system of centralized traiiic control fo a stretch of single tnack railroad betweenthe ends 'of adjacent passing sidings, electrores'ponsive means at a remote control office for desighating the directions of trail-1c in said stretch, an auxiliary. relay at said .ofiicehaving cont-acts which have a normal and anoperated' position, a code communication system including a field station at each end of said stretch connected with said oflice," a system of reversible circuits extending the length of said stretch for controlling signals governing train movement into and through said stretch in one direction or the other in accordance with traffic conditions in said stretch, means at the ends of said stretch governed, through said code communication systen'r'in accordance with the condition of said electroresponsive means for conditioning said system of reversiblecircui-ts to prepare the stretch ior'one directionof trafilc or the other and to also control the transmission of block indication codes'from one field station only for one direoe tion'of trafiic and from the other field station only for the other direction of tnaflic which show when the entire stretch is unoccupied, a block indication relay at the office for each end of said stretch governed by the block indication codes transmitted from the field station at the corresponding end of the stretch, the contacts of each block indication relay being moved to their first or their second position during receipt of an indication code according as the indication code does or does not show. that the stretch is unoccupied, means for each of said block indication relays effective during the intervals between receipt of indication codes fo controlling said relay and operative after movement of the relay contacts to their first position to cause the relay contacts to remain in their first position as long as the contacts of said auxiliary relay remain in their normal position and to cause the block indication relay contacts to move to their second position on movement of the auxiliary relay contacts to their operated position, circuit means for moving the contacts of said auxiliary relay to their operated position when said electroresponsive means is operated to change the designated direction of traffic, meansfor moving the contacts of said auxiliary relay to their normal position when the block indication relay which shows traffic conditions in the stretch for the trafiic direction designated by said electroresponsive means responds to an unoccupied indication code, means for operating said electroresponsive means to change the designated direction of traffic only when the contacts of one of said block indication relays are in their first position or the contacts of said auxiliary relay are in their operated position, a starting relay at the ofiice for each end of the stretch adapted when actuated to initiate transmission of a control code to the field station at the associated end of the stretch, and a starting button for each starting relay, each starting button controlling a circuit for actuating the associated starting relay and also controlling a, circuit for actuating the starting relay for the othe end of the stretch provided the contacts of said auxiliary relay are in their operated position.

6. In a system of centralized trafiic control for a stretch of single track railroad between the ends of adjacent passing sidings, manually controlled electroresponsive means at. a remote control ofiice for designating the direction of trafiic in said stretch, an auxiliary relay at said ofiice having contacts which have a normal and an operated position, a code communication system including a field station at each end of said stretch connected with said office, a system of reversible circuits extending the length ofsaid stretch for controlling signials governingtrain movement into and through said stretch in one direction or the other in accordance with traffic conditions in said stretch, means at the ends of said stretch governed through said code communication system in accordance with the condition of said electroresponsive means fo conditioning said system of reversible circuits to prepare the stretch for one direction of trafiic or the other and to also control the transmission of block indication codes from one field station only for one direction of trafiic and from the other field station only for the other direction of traffic which show when the entire stretch is unoccupied, a block indication relay at the oifice for each end of said stretch governed by the block indication codes transmitted from the field station at the corresponding end of the stretch, the contacts of each block indication relay being moved to thei first or their second position during receipt of an indication code according as the'indication code does or does not show that the stretch is unoccupied, means for each of said block indication relays eiTective during the intervals between receipt of indication codes for controlling said relay and operative after movement of the relay contacts to their first position to cause the relay contacts to remain in their first position as long as the contacts of said auxiliary relay remain in their normal position and to cause the block indication relay contacts to move to their second position on movement of the auxiliary relay contacts to their operated position, circuit means for moving the contacts of said auxiliary relay to their operated position when said electroresponsive means is operated to change the designated direction of trafiic, means for moving the contacts of said auxiliary relay to their normal position when the block indication relay which shows traific conditions in the stretch for the trafiic direction designated by said electroresponsive means responds to an unoccupied indication code, and means governed by said block indication relays provided the contacts of said auxiliary relay are in their normal position for indicating the occupied condition of said stretch.

7. In a system of centralized traflic control for a stretch of single track railroad between the ends of adjacent passing sidings, electroresponsive means at a remote control ofiice for designating the direction of traffic in said stretch, an auxiliary relay t said ofiice having contacts which have a normal and an operated position, a code communication system including a field station at each end of said stretch connected with said office, a system of reversible circuits extending the. length of said stretch for controlling signals governing train movement into and through said stretch in one direction or the other in accordance with trafiic conditions in said stretch, means at the ends of said stretch governed throughsaid code communication system in accordance with the condition of said electroresponsive means for conditioning said system of reversible circuits to prepare the stretch for one direction of trafiic or the other and to also control the transmission of block indication codes from one field station only for one direction of trafiic and from the other field station only for the other direction of trafiicwhich show when the entire stretch is unoccupied, a detector section at each end of the stretch including the track switch for connecting the track stretch with the adjacent passing siding, each detector section being provided with a track circuit including a track relay, a block indication relay at the-oflice for each end of said stretch governed by the block indicationcodes transmitted from the field station at the corresponding end of the stretch, the contacts of" each block indication relay being moved to their first or their second position during receipt of an indication code according asthe indication code does or does not show that the stretch is unoccupied, means for each of said block indication relays efiective during the intervals between receipt of indication codes for controlling said relay and operative after movement of the relay contacts to their first position to cause the relay contacts to remain in their first position as long as the contacts of said auxiliary relay remain in their normal position and to cause the block indication 21 relay contacts to me e to their second position on movement of the auxiliary relay contacts totheir operated position, a detector section indication relay at said oifi'ce' for each. of said detector sections, each of said detectorsection indicationrelays bein governed by the track relay for the corresponding detector. section through said code communication system, circuit means for moving the contacts of said auxiliary relay to their operated position when said electroree w sponsive means is operated "to change the designated direction. of traffic, means for moving the contacts of said auxiliary relay to their normal position when a detector section indication relay responds to an occupied indication code or when the block indication relay which shows trafiic conditions in the stretch .for the traffic direction designated by said electroresponsive means responds to an unoccupied indication code, and manually controlled means for operating said electroresponsive means to change the designated direction of traiiic provided th contacts of one of said block indication relays occupy their first position or the contacts of said auxiliary relay are in their operated position.

8'. In a system of centralized traflic control for a stretch of single track railroad between the ends of adjacent passing sidings, manually controlled electrorespo'nsive means at aremote control office for designating. the direction of traflic in said stretch; an auxiliary relay at said office having contacts which have a normal and an operated position; a code communication system including a field station at each end'of said stretch connected with said office, a; system of reversible circuits extending: the length of said stretch for controlling signals governing train movement into and through saidlstretch in one direction or the other in accordance with traflic conditions in said: stretch, means at the'ends of said stretch governed: through said code communication system in accordance with the condition of said eiectroresponsive means for conditioning said system of reversible circuits to prepare the stretch for one'direction of traflic' or the other and to also control the transmission of biock indicationcodes from'one field station only for one direction of: trafiic and from the other fieidstation only forthe other direction of trafiic which show when the entire stretch is unoccupied; a detector section at each: end of the stretch including the track switch for connecting the track stretch with the adjacent passing siding; each" detector section being provided with ar't'rack circuit including a track relay, a block indication relay at the ofiice for: each end of said stretch governed by the block indication codes transmitted from the field station atrthe corresponding end of the stretch, the contacts of each block' indication relay being moved to their first or their second position during receipt of an indication code according as the indication code does or does: not show that" the stretch is unoccupied, means .ifor each of said blockindicationrelays effective during the intervalsbetween receipt or indication codes for com trolling said relay and operative after movement of the relay contacts to their first: position to cause the relay contacts to remain in their first position as long as the contacts of said auxiliary relay remain in their normal position and to cause the block indication relay contacts to move to their second position on movement of the auxiliary relay contacts to their operated position, a detector section indication relay 22 at said-oflice for each-of said detector sections, each of said detector section indication relays being governed by the track relay for the correspondingdetectorsection through said code communication system, circuit means for moving the contacts of said auxiliary relay to their operated position when said electroresponsive means is operated to change the designated direction of traflic; means for moving the contacts of said auxiliary relaytotheir normal position when a detector section indication relay responds to an occupied indication code or when the block indication relay which shows traflic conditions in the stretch-forthe traffic direction designated by said electroresponsive means responds to an unoccupied indication code, and means governed by said electroresponsive means for indicating the designated direction of traflic provided the contacts ofsaid auxiliary relay occupy their normalposition.

9. In a, system of centralized trafiic control for a stretch of single track railroad between the ends of adjacent passing sidings, manually controlled electroresponsive means at a remote control oflioe for designating the direction of traflic in said stretch; an auxiliary relay at said ofiice having contacts which have a normal and'an operated position, a code communication system including a field station at each end of said stretch. connected with said ofiice, a system of reversible circuits xtending the length of said stretch for controlling signals governing train movement. into'and through said, stretch in one direction or. the other in accordance with traffic conditions insald stretch, means at the ends of said stretch governed. through said cod-e communication system in accordance with the condition of said-'electroresponsive means for conditioning said system or reversible circuits to preparev the stretch for one direction of traffic or the other and to also control the transmission of; block indication codes from one field station only for one direction of trafiic and from the other field. station only for the" other directionoftraflic'which' show when the entire stretch is'unoccupied', a. detector section at each end of the stretch: including the track switch for connectingthe track stretch with the adjacent passing siding; each detector section being provided with: a trackcircuit including a track relay, a block indication relay at the office for each end of said stretch governed by the block indication codes transmitted from the field station at the correspondingrendof the stretch, the contacts of each" block indication relay being moved to their first or their second position during receipt of an indicationcode according as the indication code does or does not show that the stretch is unoccupied, means for each of said block indication. relays effective during the intervals between: receipt of indication codes :for controlling said relay and operative after movement of the relay contacts to their first position to cause the relay contactscto remain in their first position as long as thecontacts of said auxiliary relay remain initheir normal position and to cause the block indication relay contacts to move to their second position on movement of the auxiliary relay contacts to their operated position, a detector section indication relay at said ofiice for each of said detector sections, each of said detector section indication relays being governed by the track relay for the corresponding detector section through said code communication system, circuit means for moving the contacts of said auxiliary relay to their operated position when said electroresponsive means is operated to change the designated direction of traflic, means for moving the contacts of said auxiliary relay to their normalposition when a detector section indication relay responds to an occupied indication code or when the block indication relay which shows-traffic conditions in the stretch for the traffic direction designated by said electroresponsive means responds to an unoccupied indication code, and means governed by said block indication relays provided the contacts of said auxiliary relay are in their normal position for indicating the occupied condition of said stretch.

10. In a system of centralized traffic control for a stretch of single track railroad between the ends of adjacent" passing sidings, electroresponsive means at a remote control office for designating the direction of trafiic in said stretch, an auxiliary relay at said ofiice having contacts which hav a normal and an operated position, a code communication system including a field station at each end of said stretch connected with said office, a system of reversible circuits extending the length of said stretch for controlling signals governing train movement into' and through said stretch in one direction or the other in accordance with traffic conditions in said stretch, means at the ends of said stretch governed through said code communication system in accordance with the condition of said electroresponsive means for conditioning said system of reversible circuits to prepare the stretch for one direction of traffic or the other and to also control the transmission from the field station at the entrance end of the stretch of block indication codes which show when the entire stretch is unoccupied, a blockindication relay at the office for each end of the stretch governed by the block indication codes transmitted from the field station at the corresponding end of the stretch, the contacts of each block indication relay being moved to their first or their second position during receipt of an indication code according as the indication code does or does not show that the stretch is unoccupied, means for each of said block indication relays eifective during the inter vals between receipt of indication codes for controlling said relay and operative after movement of the relay contacts to their first position to cause the relay contacts to remain in their first posiiton as long as the contacts of said auxiliary relay remain in their normal position and to cause the block indication relay contacts to move to their second position on movement of the auxiliary relay contacts to their operated position, circuit means for moving the contacts of said auxiliary relay to their operated position when said electroresponsive means is operated to change the designated direction of traffic, means for moving the contacts of said auxiliary relay to their normal'position when the block'indication relay for the end of the stretch designated the entrance end by said electroresponsive means responds to an unoccupied indication code, and manually controlled means for operating said electroresponsive means to change the designated traffic direction provided the contacts of one of said block indication relays occupy their first position or the-contacts of said auxiliary relay occupy their operated position.

ll. In a system' of centralized traffic control for a stretch of single track railroad between the ends of adjacent passing sidings; electroresponsive means at a, remote control office for designating the direction of traffic in said stretch, an auxiliary relay at said office having contacts which have a normal and an operated'position, a code communication system including a field station at each end of said stretch connected with said office, a system of reversible circuits extending the length of said stretch for controlling signals governing train movement into and through said stretch in one direction or the other in accordance with traffic conditions in said stretch, means at the ends of said stretch governed through said code communication system in accordance with the condition of said electroresponsive means for conditioning said system of reversible circuits to prepare the stretch for one direction'of traffic or the other and to also control the transmission from the field station at the entrance end of the stretch of block indication codes which show when the entire stretch is unoccupied, a block indication relay at the office for each-end of the stretch governed by the block indication codes transmitted from th field station at the corresponding end of the stretch, the contacts of each block-indication relay being moved to their first or their second position during receipt of an indication code according as the indication code does or does not show that the stretch is unoccupied, means for each of said block indication relays efiective during the intervals between receipt of indication codes for controlling said relay and operative after movement of the relay contacts to their first position to cause the relay contact to remain in their first position as long as the contacts of said auxiliary relay remain in their normal position and to cause the block indication relay contacts to move to their second position on movement of the auxiliary relay contacts to their operated position, circuit means for moving the contacts of said auxiliary relay to their operated position when saidelectroresponsive means is oper-' ated to change the designated direction of traific, means for moving the contacts of said auxiliary relay to their normal position when theblock indication relay for the end ofthe stretch designated the entrance end by said electrorespon sive means responds to an unoccupied indication code, manually controlled means for operating said electroresponsive means to change the designated traflic direction provided the contacts of one of said block indication relays occupy their first position or'the contacts of said auxiliary relay occupy their operated position, a starting relay' at the oifice for each end of th stretch adapted when actuated to initiate transmission of a control code to the field station at the associated end of the stretch, and a starting button for each starting relay, each starting button controlling a circuit for actuating the associated starting relay and also controlling a circuit for actuating the starting relay for the other end of the stretch provided the contacts of said auxiliary relay are in their operated position.

ARTHUR L. JEROME. 

